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The purpose of this section is to help the reader establish a uniform means of depicting and identifying all classes of instruments, instrumentation systems, and functions used for measurement, monitoring, and control. It is done by presenting a designation system of graphic symbols and identification codes.* It must be noted that a significant part of this section has been extracted from the revision work of the ISA** SP5.1 subcommittee, and much of it has been based on draft working documents being utilized at the time of this writing, documents with which one of the authors has been actively involved. Other portions of this section, dealing with certain symbols, graphics, and practical tips, are based on the authors’ experience in industry and are not part of the SP5.1 subcommittee’s proposed forthcoming revision.
General Considerations 1.1 FLOWSHEET SYMBOLS AND P&I DIAGRAMS Scope General Application to Industries Application to Work Activities Application to Classes of Instrumentation and to Instrument Functions Extent of Loop and Functional Identification Extent of Symbolization Inclusion of the New S5.1 Standard (now ANSI/ISA-5.01.01) in User/Owner Documents Definitions Related to Flowchart Diagram Symbology General Definitions Related to Flowsheet Symbology Identification System Guidelines General Instrument Index 10 Guideline Modifications 10 Multipoint, Multivariable, and Multifunction Devices 10 System Identification 10 Loop Identification Number 10 Identification Letter Tables 11 General 11 Graphic Symbol System Guidelines 19 General 19 Guideline Modifications 19 Instrument Line Symbols 19 Measurement and Control Devices and/or Function Symbols 19 Fieldbus P&ID Examples: DeviceNet 22 Multipoint, Multifunction, and Multivariable Devices and Loops 23 Fieldbus Devices, Loops, and Networks 28 Comments and Exceptions (Including NonISA Industrial Practice) 28 P&IDs: Practical Aspects and Practices in the EPC Industry 28 1.2 FUNCTIONAL DIAGRAMS AND FUNCTION SYMBOLS 31 ISA Functional Diagramming (EX-SAMA) 31 Instrument and Control Systems Functional Diagramming 31 Equivalent P&ID Loop, Functional Instrument and Electrical Diagrams 31 Functional Diagramming Symbol Tables 32 1.3 INSTRUMENT TERMINOLOGY AND PERFORMANCE 46 Introductory Notes 46 Operating Conditions vs Performance Sources and References 47 Definition of Terms 47 Test Procedures 74 Calibration Cycle 75 47 © 2003 by Béla Lipták General Considerations Calibration Curve 75 Test Procedures 75 References 77 1.4 SYSTEM ACCURACY Configuration Tools 94 Device Configuration 95 Identification 96 Calibration 97 Monitoring 98 Simulation 98 Diagnostics 98 Reference 99 78 Definitions of Terms 78 Language, Terminology, and Reality 78 Clarifying the “Accuracy” Statement 79 Terminology of Inaccuracy and Repeatability The Accuracy Statement 80 Flow Measurement Example 80 Analog and Linear Devices—Traditional Magnetic Flowmeters 81 Analog, Nonlinear—Orifice Plates 81 Digital Linear—Turbine Flowmeter 82 Combined System Accuracy 83 Basis 83 Basis 83 Temperature and Pressure Effects 84 Repeatability vs Total Error 85 References 85 Bibliography 85 1.5 UNCERTAINTY CALCULATIONS 79 86 Uncertainty and Error 86 Classifying Error Sources and Their Uncertainties 87 The ISO Classification of Errors and Uncertainties 87 ISO Type A Uncertainties and Errors 87 ISO Type B Uncertainties and Errors 87 Engineering Classification of Errors and Uncertainties 89 Random Errors and Uncertainties 89 Systematic Errors and Uncertainties 89 Total Uncertainty 90 ISO Total Uncertainty 90 Engineering Total Uncertainty 90 Calculation Example 90 ISO Uncertainty Calculation Example 91 Engineering Uncertainty Calculation Example 91 Summary 91 References 91 Bibliography 92 1.6 CONFIGURING INTELLIGENT DEVICES Design Feature Recommendations Costs 93 Introduction 93 © 2003 by Béla Lipták 93 93 1.7 INSTRUMENT INSTALLATION 100 Cost 100 Installation Documentation 100 Physical vs Schematic Documents 100 Safety in Design 100 Pipe and Tube Material 102 Electrical Installations in Potentially Explosive Locations 103 Physical Support 103 Process Industries Practices 104 Bibliography 104 1.8 INSTRUMENT CALIBRATION 108 Introduction 108 Calibration of Pressure Sensors 108 As-Found and As-Left Data 109 Hysteresis 110 Calibration Traceability 110 Linearity and Damping Adjustments 110 Automated Calibration Equipment 111 Calibration of Temperature Sensors 111 Calibration Intervals 112 Calibration of Smart Instruments 112 Assessment of Accuracy 112 Calibration and Range Setting 112 References 113 1.9 RESPONSE TIME AND DRIFT TESTING 114 Fundamentals of Response Time Testing 114 Laboratory Testing 115 Testing of Temperature Sensors 115 Testing of Pressure Sensors 115 In Situ Response Time Testing 116 Testing of Temperature Sensors 117 Testing RTDs 117 Testing Thermocouples 118 Analysis of LCSR Test Results 119 Applications of LCSR Testing 120 In Situ Testing of Pressure Sensors 121 Analyzing of Noise Data 121 On-Line Verification of Calibration 122 Contents of Chapter Drift Evaluation Using Multiple Sensors 122 Empirical Models, Neural Networks 123 References 125 1.10 REDUNDANT AND VOTING SYSTEMS 126 Introduction 126 Hardware Redundancy 126 Software Redundancy 127 Fault-Tolerant Computer System Design 128 Field Instrument Redundancy and Voting 129 Single-Transmitter Configuration 129 Two-Transmitter Configuration 130 Three-Transmitter Configuration 130 Diagnostic Coverage 130 Engineering Redundant Measures 132 Complex Control Loops 132 Final Control Elements 132 Availability Considerations 133 References 134 Bibliography 134 © 2003 by Béla Lipták 1.11 INSTRUMENT EVALUATION 136 Evaluation Results 136 Organization 137 Evaluation Methodology 137 System Configuration 137 System Functions 139 Properties 139 Test Conditions 140 Evaluation Techniques 140 Relevant Standards 141 Bibliography 141 1.12 BINARY LOGIC DIAGRAMS 142 Logic Diagrams 142 Logic Symbols 143 Preparation of Logic Diagrams 143 Diagram Interpretation 146 Active and Passive Logic 148 Final Caution 148 Bibliography 149 1.1 Flowsheet Symbols and P&I Diagrams* G PLATT (1982) B G LIPTÁK (1995) The purpose of this section is to help the reader establish a uniform means of depicting and identifying all classes of instruments, instrumentation systems, and functions used for measurement, monitoring, and control It is done by presenting a designation system of graphic symbols and identification codes.* It must be noted that a significant part of this section has been extracted from the revision work of the ISA** SP5.1 subcommittee, and much of it has been based on draft working documents being utilized at the time of this writing, documents with which one of the authors has been actively involved Other portions of this section, dealing with certain symbols, graphics, and practical tips, are based on the authors’ experience in industry and are not part of the SP5.1 subcommittee’s proposed forthcoming revision A disclaimer to any future ISA standards documents is hereby stated: The reader is cautioned that the draft ISA document that provided much of the information in this section has not been approved as of the time of this writing It cannot be presumed to reflect the position of ISA or any other committee, society, or group The intent is to pass along to the reader the best and latest thinking on this subject at this point in time, although many items are contentious and are ultimately subject to change in the continuously evolving fields of digital control systems and digital data buses Another view of flowsheet and piping and instrument diagram (P&ID) symbols and diagrams covered in this section is in terms of practical aspects and practices used by instrumentation and control practitioners in the engineering, procurement, and construction (EPC) industry SCOPE** General The procedural needs of various users are different, and these differences are recognized, when they are consistent with the objectives of this standard, by providing alternative symbol and identification methods * Used with permission of the Instrument, Systems and Automation Society **Formerly called the Instrument Society of America © 2003 by Béla Lipták J E JAMISON, A ROHR (2003) A limited number of examples are provided later that illustrate (with the emphasis on digital systems/loops) how to accomplish the following: a) Design an identification system and construct an identification number b) Use graphic symbols to construct the following: 1) Schematic diagrams of instrument devices and functions in monitoring and control loops 2) Schematic and ladder diagrams of electrical circuits c) Add information and simplify diagrams Examples of symbol applications are generally shown as applied in the oil and chemical processing industries as in the original version of this standard, but the principles shown are applicable to most other industries Specific applications are to be addressed in greater detail and will be forthcoming in the planned S5.1 (now ANSI/ISA5.01.01) series of Technical Reports dedicated to the various processing, generating, and manufacturing industries These will include processes such as continuous and batch chemical, oil, and metal refining, pulp and paper, water and waste treatment, power generation and distribution, and discrete parts manufacturing Application to Industries The proposed revised ISA S5.1 (now ANSI/ISA-5.01.01) standard will be suitable for use in the above-mentioned process industries and in discrete parts manufacturing where the use of control system schematic and functional diagramming is required to describe the relationship with processing equipment and the functionality of measurement and control equipment Certain fields, such as astronomy, navigation, and medicine, use very specialized instruments that are different from conventional industrial process instruments No specific effort was made to have the ISA standard meet the requirements of those fields However, it is expected that, in certain areas such as control functional diagrams, they will prove applicable for such specialized fields 1.1 Flowsheet Symbols and P&I Diagrams Application to Work Activities The proposed revised ISA S5.1 (now ANSI/ISA-5.01.01) standard will be suitable for use whenever reference to measurement and control instrumentation, control device functions, or software applications functions is required for the purposes of symbolization and identification Such references may be required for the following uses as well as others: a) b) c) d) e) f) g) h) i) j) Design sketches Teaching examples Technical papers, literature, and discussions Instrumentation system diagrams, loop diagrams, logic diagrams, and functional diagrams Functional descriptions Conceptual drawings: process flow diagrams (PFDs) and utility flow diagrams (UFDs) Construction drawings: engineering flow diagrams (EFDs), mechanical flow diagrams (MFDs), piping and instrument diagrams (P&IDs), and system flow diagrams (SFDs) Specifications, purchase orders, manifests, and other lists Identification and tag numbering of instruments and control functions Installation, operating, and maintenance instructions, drawings, and records The standard is intended to provide sufficient information to enable anyone with a reasonable amount of process and instrumentation knowledge to understand the methods of measurement and process control It is not necessary to possess the detailed knowledge of a specialist in instrumentation and control systems to understand the standard Application to Classes of Instrumentation and to Instrument Functions The symbolism and identification methods provided in the standard are applicable to all classes and types of measurement and control instruments and functions The methods can be used for, but are not limited to, describing and identifying the following: a) b) c) d) e) Discrete (individual) instruments and their functions Shared display and control functions Distributed control functions Computer control functions Programmable logic controller display and control functions f) Application software display and control functions Extent of Loop and Functional Identification The ISA S5.1 standard (now ANSI/ISA-5.01.01) provides identification codes and methods for the alphanumeric identification of monitoring and controlling loops, instruments, © 2003 by Béla Lipták and functions The user is free to apply additional identification by serial, equipment, unit, area, or plant number or any other additional means required for the unique identification of a loop, instrument, or function A unique function identification number shall identify each instrument, its inherent functions, and each configurable function that requires or allows a user-assigned, unique microprocessor or computer address required by a loop Extent of Symbolization The standard provides symbol sets for the graphic depiction of limited or total functionality for instruments and other devices, entire monitor/control loops, or control circuits The amount of detail to be shown by the use of symbols depends on the purpose and audience for which the document is being prepared A sufficient number of symbols should be used to show the functionality of the instrumentation and control loop being depicted However, it is not considered necessary to provide a symbol for each instrument device and each function within a loop Additional construction, fabrication, installation, and operation details of an instrument are better described in a suitable specification, data sheet, drawing, sketch, or other document intended for individuals who require such details Inclusion of the New S5.1 Standard (now ANSI/ISA-5.01.01) in User/Owner Documents This is a new concept in ISA standards at this point in time Mandatory use of the standard is required by users/owners based on the following statements When the latest issue of the standard is included in user/owner’s engineering and/or design guidelines or standards by reference and a) “Without exception,” then the standard in its entirety shall be mandatory b) “With exceptions,” then the parts of the standard: 1) “Excepted to” shall be fully described and detailed 2) “Not excepted to” shall be mandatory When a previous issue of the standard is included by reference with or without exception in user/owner’s engineering and design guidelines or standards, that standard in part or in its entirety shall be mandatory until such time as the user/owner’s guidelines or standards are revised When the new issue is used as a guide in the preparation of user/owner’s guidelines or standards, symbols and letter and symbol meanings different from those in the standard shall be fully described and detailed Symbols and the meanings of letters and symbols from previous issues of the S5.1 standard (now ANSI/ISA-5.01.01) that are different from those contained in this new issue may continue to be used, provided that they are fully described and detailed General Considerations DEFINITIONS RELATED TO FLOWCHART DIAGRAM SYMBOLOGY See statement of permission on page General For the purpose of understanding the ISA S5.1 standard (now ANSI/ISA-5.01.01), the following definitions and terminology apply For a more complete treatment, see ISA-S51.1 and the ISA-S75 series of standards Terms italicized within a definition are also defined in this clause Definitions Related to Flowsheet Symbology Accessible A feature of a discrete device function or feature of an interactive shared system function or feature that can be used or seen by an operator for the purpose of performing control operations, such as setpoint changes, auto-manual transfer, or on–off operations Alarm An indicating instrument that provides a visible and/or audible indication if and when the value (or rate of change value) of a measured or initiating variable is out of limits, has changed from a safe to an unsafe condition, and/or has changed from a normal to an abnormal operating state or condition a) Actuation may be by binary switch or function or analog transmitter or function b) Indication may be by annunciator panel, flashing light, printer, buzzer, bell, horn, siren, and/or shared graphic display systems Analog A signal or device that has no discrete positions or states and changes value as its input changes value When used in its simplest form, as in “analog signal” as opposed to “binary signal,” the term denotes a continuously varying quantity Application software Software specific to a user application that is configurable and in general contains logic sequences, permissive and limit expressions, control algorithms, and other code required to control the appropriate input, output, calculations, and decisions See also software Assignable A system feature permitting channeling or directing of a signal from one device to another without the need for changes in wiring either by means of patching, switching, or via keyboard commands to the system Auto-manual station A manual loading station or control station that also provides switching between manual and automatic control modes of a control loop See also manual loading station Balloon An alternative term for the circular symbol used to denote and identify the purpose of an instrument or function that may contain a tag number See preferred term, bubble © 2003 by Béla Lipták Behind the panel A location that, in a broad sense, means “not normally accessible to an operator,” such as the rear of an instrument or control panel, an enclosed instrument rack or cabinet, or an instrument rack room within an area that contains a panel Binary A signal or device that has only two discrete positions/states and, when used in its simplest form, as in “binary signal” as opposed to “analog signal,” the term denotes an “on–off ” or “high–low” state Board A freestanding structure consisting of one or more sections, cubicles, or consoles that has groups of discrete (individual) instruments mounted on it, houses the operator–process interface, and is chosen to have a unique designation See panel Bubble The preferred term for the circular symbol used to denote and identify the purpose of an instrument or function that may contain a tag number See alternative term, balloon Communication link A wire, cable, or transmitter network or bus system that connects dedicated microprocessor-based and computer-based systems so that they share a common database and communicate according to a rigid protocol in a hierarchical and/or peer-to-peer relationship See also data link a) Wires or cables may be of twisted pair, coaxial, telephone, or fiber optic construction b) Transmitters may be radio, telephone, and/or microwave devices Computer control system A system in which all control action takes place within a control computer, such as a mainframe computer or minicomputer, which may be single or redundant Computing device Preferred term for a device that performs one or more calculations or logic operations, or both, and transmits one or more resultant output signals See also computing relay Computing function A hardware or software function that performs one or more calculations or logic operations, or both, and transmits one or more resultant output signals Computing relay Alternative term for a device that performs one or more calculations or logic operations, or both, and transmits one or more resultant output signals See also computing device Configurable A term for devices or systems whose functional or communication characteristics can be selected or rearranged through setting of program switches, application software, fill-in-the-blank forms, pull-down menus, entered values or text, or other methods other than rewiring as a means of altering the configuration Controller A device having an output that varies to regulate a controlled variable in a specified manner that may be a self-contained analog or digital instrument or may be the equivalent of such an instrument in a shared-control system 1.1 Flowsheet Symbols and P&I Diagrams a) An automatic controller varies its output automatically in response to a direct or indirect input of a measured process variable b) A manual controller, or manual loading station, varies its output in response to a manual adjustment; it is not dependent on a measured process variable c) A controller may be an integral element of other functional elements of a control loop Control station A manual loading station that also provides switching between manual and automatic control modes of a control loop See also auto-manual station a) The operator interface of a distributed control system may be referred to as a control station Control valve A device, other than a common, handactuated process block valve or self-actuated check valve, that directly manipulates the flow of one or more fluid process streams a) The designation “hand control valve” shall be limited to hand-actuated valves that, when used for process throttling, require identification as an instrument or control device Converter A device that receives information as one form of an instrument signal and transmits an output signal as another form, such as a current to pneumatic signal converter a) An instrument that changes a sensor’s output to a standard signal is properly designated as a transmitter and not a converter Typically, a temperature element (TE) connects to a transmitter (TT) and not to a converter (TY) b) A converter is sometimes referred to as a transducer, a completely general term not recommended for signal conversion Data link A wire, cable, or transmitter network or bus system that connects field located devices with dedicated microprocessors so that they share a common database and communicate according to a rigid protocol in a hierarchical or peer-to-peer relationship to other such devices and/or compatible microprocessorbased systems See also communication link a) Wire or cable may be of twisted-pair, coaxial, telephone, or fiber optic construction b) Transmitters may be radio, telephone, or microwave devices Detector A device that is used to detect the presence of something, such as flammable or toxic gases or discrete parts See also primary element and sensor Device A piece of instrument hardware that is designed to perform a specific action or function, such as a controller, indicator, transmitter, annunciator, or control valve Digital A signal or device that generates or uses binary digit signals to represent continuous values or discrete states Discrete A term used to describe the following: © 2003 by Béla Lipták a) Signals that have any number of noncontinuous distinct or defined states or positions Binary signals are a subset See binary b) Instruments or devices that have separate or individual entities, such as a single-case controller or recorder Distributed control system Instrumentation, input/output devices, control devices, and operator interface devices that, in addition to executing stated control and indication functions, permits transmission of control, measurement, and operating information to and from single- or multiple-user specifiable locations, connected by single or multiple communication links Field instrument An instrument that is not mounted on a panel or console or in a control room but commonly in the vicinity of its primary element or final control element See local instrument Final control element A device, such as a control valve, that directly controls the value of the manipulated variable of a control loop Function The purpose of, or the action performed by, a device or application software Identification The sequence of letters or digits, or both, used to designate an individual instrument, function, or loop Instrument A device used for direct or indirect measurement, monitoring, or control of a variable a) Includes primary elements, indicators, controllers, final control elements, computing devices, and electrical devices such as annunciators, switches, and pushbuttons b) Does not apply to an instrument’s internal components or parts, such as receiver bellows or resistors Instrumentation A collection of instruments or functions or their application for the purpose of measuring, monitoring, controlling, or any combination of these Local instrument An instrument that is not mounted on a panel or console or in a control room but commonly is in the vicinity of its primary element or final control element See field instrument Local panel A panel that is not a central or main panel and is commonly located in the vicinity of plant subsystems or subareas (sometimes called a local instrument panel) a) The term local panel instrument should not be confused with local instrument or local instrument panel Loop A combination of two or more instruments or control functions arranged so that signals pass from one to another for the purpose of measurement indication or control of a process variable Manual loading station A device or function that has a manually adjustable output and may also have indicators, lights, and/or other functions that are used General Considerations to actuate or modulate one or more devices It does not provide switching between auto-manual modes of a control loop Measurement The determination of the existence or magnitude of a process variable Monitor A general term for an instrument or instrument system used to measure or sense the status or magnitude of one or more variables for the purpose of deriving useful information This sometimes means an analyzer, indicator, or alarm Monitor light A light that indicates which of a number of normal (but not abnormal) conditions of a system or device exists See also pilot light Multifunction devices Devices (controllers) that receive one or more input signals and send out two or more output signals or perform two or more functions See multipoint and multivariable devices Multipoint devices Indicators or recorders that may be single or multivariable type and that receive input signals from two or more primary elements or transmitters See multifunction devices and multivariable devices Multivariable devices Devices (indicators, recorders, or controllers) that receive two or more input signals and send one output signal See multifunction and multipoint devices Panel A freestanding or built-in structure, consisting of one or more sections, cubicles, consoles, or desks, in which groups of instrument hardware are mounted It could house the operator–process interface and is given a unique designation Panel-mounted An instrument or other device that is mounted in a panel or console and is accessible for an operator’s normal use a) A function that is normally accessible to an operator in a shared-display system is the equivalent of a discrete panel-mounted device Pilot light A light that indicates which of a number of normal conditions of a system or device exists It is not an alarm light that indicates an abnormal condition See also monitor light Primary element An external or internal instrument, or a system element, that quantitatively converts the measured variable into a form suitable for measurement See also detector and sensor: a) An orifice plate is an external primary element b) The sensing portion of a transmitter is an internal primary element Process Any operation or sequence of operations involving a change of energy, state, composition, dimension, or other properties that may be defined with respect to zero or some other defined initial value Process variable Any measurable property of a process Used in this standard to apply to all variables other than instrument signals between devices in a loop © 2003 by Béla Lipták Program A repeatable sequence of actions that defines the state of outputs as a fixed relationship to the state of inputs Programmable logic controller A controller, usually with multiple inputs and outputs, that contains an alterable program that is a) Typically used to control binary and/or discrete logic or sequencing functions b) Also used to provide continuous control functions Relay A device whose function is to pass on information in an unchanged form or in some modified form; often used to mean the preferred term, computing device a) Relay is a term applied specifically to an electric, pneumatic, or hydraulic switching device that is actuated by a signal, and to functions performed by a relay Scan To sample or multiplex, in a predetermined manner, each of a number of variables periodically and/or intermittently a) A scanning or multiplexing device is often used to ascertain the state or value of a group of variables and may be associated with other functions such as recording and alarming Sensor A separate or integral part, or function, of a loop or an instrument that first senses the value of a process variable It assumes a corresponding predetermined and intelligible state and/or generates an output signal indicative of or proportional to the process variable See also detector and primary element Setpoint An input variable that sets the desired value of the controlled variable manually, automatically, or by means of a program in the same units as the controlled variable Shared control A feature of a control device or function that contains a number of preprogrammed algorithms that are user retrievable, configurable, and connectable It allows user-defined control strategies or functions to be implemented and is often used to describe the control features of a distributed control system a) Control of multiple process variables can be implemented by sharing the capabilities of a single device of this kind Shared display The operator interface device (such as video, light emitting diode, liquid crystal, or other display unit) used to display process control information from a number of sources at the command of the operator It is often used to describe the visual features of a distributed control system Software The programs, codes, procedures, algorithms, patterns, rules, and associated documentation required for the operation or maintenance of a microprocessor- or computer-based system See also application software 1.1 Flowsheet Symbols and P&I Diagrams Software link The interconnection of system components via communications networks or functions via software or keyboard instruction Supervisory setpoint control system The generation of setpoint or other control information by a computer control system for use by shared control, shared display, or other regulatory control devices Switch A device that connects, disconnects, selects, or transfers one or more circuits and is not designated as a controller, relay, or control valve As a verb, the term is also applied to a function performed by a switch Test point A process connection to which no instrument is permanently connected; it is intended for the temporary or intermittent connection of an instrument Transducer A general term for a device, which can be a primary element, transmitter, relay, converter, or other device, that receives information in the form of one or more physical quantities, modifies the information or its form if required, and produces a resultant output signal Transmitter A device that senses a process variable through the medium of a sensor or measuring element and has an output whose steady-state value varies only as a predetermined function of the process variable The sensor can be an integral part, as in a direct connected pressure transmitter, or a separate part, as in a thermocouple-actuated temperature transmitter IDENTIFICATION SYSTEM GUIDELINES See statement of permission on page General This subsection establishes an identification system for instrument loop devices and functions It is logical, unique, and consistent in application with a minimum of exceptions, special uses, and requirements The identification system is used to identify instrumentation in text, sketches, and drawings when used with graphic symbols as described in the subsection titled “Graphic Symbol System Guidelines.” The identification system provides methods for identifying instrumentation required to monitor, control, and operate a processing plant, unit operation, boiler, machine, or any other system that requires measurement, indication, control, modulation, and/or switching of variables Primary instrumentation, hardware and software devices, and functions that measure, monitor, control, and calculate, and application software functions that require or allow userassigned identities, shall be assigned both loop and functional identification Secondary instrumentation, such as hardware devices that measure and monitor, as well as level glasses, pressure gauges, and thermometers, shall be assigned only a functional identification © 2003 by Béla Lipták Loop and functional identification shall be assigned in accordance with the guidelines in the standard or with modified guidelines based on the standard, established by the user or owner of the plant, unit, or facility in which the instrumentation is to be installed A unique loop identification number shall be assigned to identify each monitoring and control loop A unique instrument identification/tag number based on the loop identification number shall be assigned for each monitoring or control loop to identify each of the following: a) Hardware device and integral functions b) Application software functions that require or allow a user-assigned unique microprocessor or computer address A monitor or control loop consists of some or all of the following (as indicated): a) Measurement of the process variable (monitor and control): 1) Measuring element device, such as an orifice plate or thermocouple 2) Measurement transmitter, with an integral measuring element, such as a pressure transmitter or without an integral measuring element, such as a temperature transmitter and thermocouple b) Conditioning of the measurement or input signal (monitor and control): 1) Calculating devices 2) Calculating functions 3) Safety barriers c) Monitoring of the process variable (monitor): 1) Indicating or recording device 2) Application software display function d) Controlling of the process variable (control): 1) Indicating or recording control device 2) Application software control function e) Conditioning of the controller or output signal (control): 1) Calculating devices 2) Calculating functions f) Modulation of the manipulated variable (control): 1) Control valve modulation or on–off action 2) Manipulation of another control loop setpoint 3) Limiting another control loop output signal Secondary instrumentation shall be assigned instrument identification/tag numbers or other forms of identification in accordance with the guidelines established in the ISA standard or with modified guidelines based on the standard established by the user/owner of the plant, unit, or facility in which the instrumentation is to be installed Examples of instrument identification systems will be found in a future series of S5.1 (now ANSI/ISA-5.01.01) Technical Reports 10 General Considerations Instrument Index Loop identification numbers and instrument identification/ tag numbers shall be recorded in an instrument index (either manually generated or computerized instrument database), which shall be maintained for the life of the facility for the recording and control of all documents and records pertaining to the loops and their instrumentation and functions An instrument index shall contain references to all instrumentation data required by owner or government regulatory agency management-of-change requirements It should contain, as a minimum, for each loop: a) b) c) d) e) f) g) Loop identification number Service description Instrument identification/tag numbers Piping and instrument (P&ID) drawing numbers Instrument data sheet numbers Location plan numbers Installation detail drawing numbers Guideline Modifications These guidelines may be modified to suit the requirements of the following: a) Existing user-designed identification and numbering schemes that are not included in this standard b) Computer databases used for record keeping c) Microprocessor-based monitoring or control systems When modified guidelines are adopted, they shall be fully described and detailed in the user/owner’s engineering or design standards Multipoint, Multivariable, and Multifunction Devices Input and output devices and functions that are components of a multipoint device shall have tag suffixes that delineate between the different components Multivariable devices that receive two or more input signals, transmit one output signal, and have been assigned measured/initiating variable multivariable [U], shall have the following indicators: a) Each different input shall be assigned its own loop identification number, and each output indicating, recording, switching, alarming, or other device and function that is actuated solely by a single variable, shall be assigned an instrument/tag number that identifies it as part of these loops b) Each indicating, recording, switching, alarming, or other device or function that is actuated by more than one of the multivariables shall be assigned an instrument/tag number that identifies it as part of the multivariable loop © 2003 by Béla Lipták Multifunction devices that receive two or more input signals, send out two or more output signals, or perform two or more functions may be assigned readout/passive or output/ active function multifunction [U] and shall have a loop number assigned according to the measured/initiating variable Loops that perform two or more functions from a single measured/initiating variable may have the following: a) Each function assigned a unique instrument/tag number and shown on diagrams as multiple tangent bubbles for the integral functions and multiple individual bubbles for the nonintegral functions b) One readout/passive and/or output/active function designated by succeeding letter [U], for the integral functions and multiple individual bubbles for the nonintegral functions, and, if necessary, a note or comment defining the integral functions Graphic symbol examples of these loops are given later in this section System Identification Instrumentation is often assembled into systems for various reasons including ease of purchase, ease of application, compatibility, and so on These systems may need to be identified on drawings and in text Some of the more common instrumentation systems and the system codes for identifying them are the following: ACS = Analyzer control system BMS = Burner management system CCS = Computer control system CEMS = Continuous emissions monitoring system DCS = Distributed control system FDS = Flame detection system MMS = Machine monitoring system PCCS = Personal computer control system PLC = Programmable logic controller SIS = Safety instrumented system VMS = Vibration monitoring system Suffixes may be added to the instrumentation system codes [SC] when required as follows: a) [SC] 1, [SC] 2, and so forth, when more than one system is used in a complex b) [SC]-M, [SC]-L, when main and local systems are used in a unit c) [SC]-[unit identifier] Loop Identification Number A loop identification number is a unique combination of letters and numbers that is assigned to each monitoring and control loop in a facility to identify the process or machine variable that is being measured for monitoring or control (see Table 1.1a) 16 A(1) Absolute Alarms First Letters Measured/Initiating Variable B E G I L N O P Q R W X User’s Choice Sensor, Primary Element Gauge, Glass (2) Indicate Light User’s Choice Orifice Restrict Point (Test Conn.) Integrate Totalize Unclassified Deviation Alarms Record Well TF Temperature ratio TFAH TFAM TFAL TFAD TFADH TFADL N/A N/A TFI N/A N/A N/A N/A TFR N/A TK Temperature schedule TKAH TKAM TKAL TKAD TKADH TKADL N/A N/A TKI TKL N/A N/A N/A TKR N/A H M L D DH DL U Multivariable N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A V Vibration, machine analysis VAH N/A VAL VAD VADH VADL VE VG VI N/A N/A VP N/A VR N/A W WD Weight, force Weight difference WAH WAM WAL WAD WAD WADL WE N/A WI WL N/A N/A N/A WR N/A WDAH WDAM WDAL WDAD WDAD WDADL WE N/A WDI WDL N/A N/A N/A WDR N/A WF Weight ratio WFAH WFAM WFAL WFAD WFAD WFADL WE N/A WFI N/A N/A N/A N/A WFR N/A WK Weight loss (gain) WKAH WKAM WKAL WKAD WKAD WKADL N/A N/A WKI WKL N/A N/A N/A WKR N/A WQ Weight total WQAH WQAM WQAL WQAD WQAD WQADL N/A N/A WQI WQL N/A N/A N/A WQR N/A X Unclassified XAH XAM XAL XAD XAD XADL XE XG XI XL N/A N/A N/A XR N/A Y Event, state, presence YSAH N/A YAL N/A N/A N/A N/A YG YI YL N/A N/A N/A YR N/A Z Position, dimension ZAH ZAM ZAL ZAD ZADH ZADL ZE ZG ZI ZL N/A N/A N/A ZR N/A ZXAH ZXAM ZXAL ZXAD ZXADH ZXADL ZXE ZXG ZXI ZXL N/A N/A N/A ZXR N/A ZYADH ZYADL ZYE ZYG ZYI ZYL N/A N/A N/A ZYR N/A ZZADH ZZADL ZZE ZZG ZZI ZZL N/A N/A N/A ZZR N/A ZDADL ZDE ZDG ZDI N/A N/A N/A N/A ZDR N/A ZX Position, X-axis ZY Position, Y-axis ZYAH ZYAM ZYAL ZYAD ZZ Position, Z-axis ZZAH ZZAM ZZAL ZZAD ZD Gauge deviation ZDAH ZDAM ZDAL ZDAD ZDADH ZDX Gauge X-axis deviation ZDXAH ZDXAM ZDXAL ZDXAD ZDXADH ZDXADL ZDXE ZDXG ZDXI N/A N/A N/A N/A ZDXR N/A ZDY Gauge Y-axis deviation ZDYAH ZDYAM ZDYAL ZDYAD ZDYADH ZDYADL ZDYE ZDYG ZDYI N/A N/A N/A N/A ZDYR N/A ZDZ Gauge Z-axis deviation ZDZAH ZDZAM ZDZAL ZDZAD ZDZADH ZDZADL ZDZE ZDZG ZDZI N/A N/A N/A N/A ZDZR N/A See statement of permission on page N/A = not allowed Note (1): Alarm combinations are given with Function Modifiers for deviation from set point and absolute values Adding [H] or [L] forms low–low and high–high alarm Functional Identifications Note (2): Readout/Passive Function [G] (glass, gauge) is shown for local direct connected devices, such as flow sight glasses, level glasses, pressure gauges, and thermometers, and also for weigh scales and position indicators These devices provide a simple view of a process condition The Readout/Passive Function [I] (indicate) may continue to be used in facilities where it is currently used © 2003 by Béla Lipták General Considerations TABLE 1.1e Continued Allowable Readout/Passive Function Identification Letter Combinations TABLE 1.1f Allowable Output/Active Function Identification Letter Combinations C First Letters Measured/ Initiating Variable K Controller C(4)(5) IC(3) RC(3) CV(6) Control Station S T Switch Transmitter H M L U V Valve Damper Louver Unclassified T IT RT Multifunction X Y Z Compute Convert Actuator Relay Drive A Analysis AC AIC ARC N/A AK ASH ASM ASL AT AIT ART AU AV AX AY B Burner, combustion BC BIC BRC N/A BK BSH BSM BSL BT BIT BRT BU BV BX BY C User’s choice CC CIC CRC CK CSH CSM CSL CT CIT CRT CU CV CX CY D User’s choice DC DIC DRC DK DSH DSM DSL DT DIT DRT DU DV DX DY E Voltage EC EIC ERC N/A EK ESH ESM ESL ET EIT ERT EU N/A EX EY BZ EZ F Flow, flow rate FC FIC FRC FCV FK FSH FSM FSL FT FIT FRT FU FV FX FY FF Flow ratio FFC FFIC FFRC N/A FFK FFSH FFSM FFSL N/A N/A N/A N/A N/A FFX FFY FQ Flow total FQC FQIC FQRC FQCV FQK FQSH FQSM FQSL FQT FQIT FQRT N/A FQV FQX FQY G User’s choice GC GIC GRC GK GSH GSM GSL GT GIT GRT GU GV GX GY H Hand HC HIC N/A HCV N/A N/A N/A N/A N/A N/A N/A N/A HV HX HY I Current IC IIC IRC N/A IK ISH ISM ISL IT IIT IRT IU N/A IX IY IZ J Power JC JIC JRC N/A JK JSH JSM JSL JT JIT JRT JU N/A JX JY JZ K Time KC KIC KRC N/A N/A KSH KSM KSL N/A N/A N/A N/A N/A KX KY LCV Level LC LIC LRC User’s choice MC MIC MRC LK LSH LSM LSL LT LIT LRT LU LV LX LY MK MSH MSM MSL MT MIT MRT MU MV MX MY N User’s choice NC NIC NRC NK NSH NSM NSL NT NIT ORT NU NV NX NY O User’s choice OC OIC ORC OK OSH OSM OSL OT OIT BRT OU OV OX OY P Pressure PC PIC PRC PCV PK PSH PSM PSL PT PIT PRT PU PV PX PY PD Pressure differential PDC PDIC PDRC PDCV PDK PDSH PDSM PDSL PDT PDIT PDRT PDU PDV PDX PDY PF Pressure ratio PFC PFIC PFRC N/A PFK PFSH PFSM PFSL N/A N/A N/A N/A N/A PFX PFY PK Pressure schedule PKC PKIC PKRC N/A PKADH PKSH PKSM PKSL N/A N/A N/A N/A N/A PKX PKY Q Quantity QC QIC QRC QCV QADH QSH QSM QSL QT QIT QRT QU N/A QX QY R Radiation RC RIC RRC N/A RADH RSH RSM RSL RT RIT RRT RU RV RX RY S Speed SC SIC SRC SCV SADH SSH SSM SSL ST SIT SRT SU SV SX SY T Temperature TC TIC TRC TCV TADH TSH TSM TSL TT TIT TRT TU TV TX TY TD Temperature differential TDC TDIC TDRC N/A TDADH TDSH TDSM TDSL TDT TDIT TDRT TDU TDV TDX TDY 1.1 Flowsheet Symbols and P&I Diagrams L M © 2003 by Béla Lipták 17 (Continued) 18 TABLE 1.1f Continued Allowable Output/Active Function Identification Letter Combinations First Letters Measured/ Initiating Variable K Controller C(4)(5) IC(3) RC(3) CV(6) Control Station H S T Switch Transmitter M L T IT RT U V Multifunction Valve Damper Louver X Unclassified Y Compute Convert Actuator Relay Drive TF Temperature ratio TFC TFIC TFRC N/A TFADH TFSH TFSM TFSL N/A N/A N/A N/A N/A TFX TFY TK Temperature schedule TKC TKIC TKRC N/A TKADH TKSH TKSM TKSL N/A N/A N/A N/A N/A TKX TKY U Multivariable UC UIC URC N/A N/A USH USM USL UT N/A N/A N/A N/A UX UY V Vibration, machine analysis VC VIC VRC N/A VADH VSH VSM VSL VT VIT VRT N/A N/A VX VY W WD Weight, force Weight difference Z WC WIC WRC WCV WAD WSH WSM WSL WT WIT WRT WU WV WX WY WDC WDIC WDRC N/A WDAD WDSH WDSM WDSL WDT WDIT WDRT WDU N/A WDX WDY WF Weight ratio WFC WFIC WFRC N/A WFAD WFSH WFSM WFSL N/A N/A N/A N/A N/A WFX WFY WK Weight loss (gain) WKC WKIC WKRC N/A WKAD WKSH WKSM WKSL N/A N/A N/A N/A N/A WKX WKY WQ Weight total WQC WQIC WQRC N/A WQAD WQSH WQSM WQSL N/A N/A N/A N/A N/A WQX WQY X Unclassified XC XIC XRC N/A XAD XSH XSM XSL XT XIT XRT XU XV XX XY XZ Y Event, state, presence YC YIC YRC N/A N/A YSH YSM YSL YT YIT YRT YU N/A YX YY YZ Z Position, dimension ZC ZIC ZRC N/A ZADH ZSH ZSM ZSL ZT ZIT ZRT ZU ZV ZX ZY ZZ ZX Position, X-axis ZXC ZXIC ZXRC N/A ZXADH ZXSH ZXSM ZXSL ZXT ZXIT ZXRT N/A ZXV ZXX ZXY ZXZ ZY Position, Y-axis ZYC ZYIC ZYRC N/A ZYADH ZYSH ZYSM ZYSL ZYT ZYIT ZYRT N/A ZYV ZYX ZYY ZYZ ZZ Position, Z-axis ZZC ZZIC ZZRC N/A ZZADH ZZSH ZZSM ZZSL ZZT ZZIT ZZRT N/A ZZV ZZX ZZY ZZZ ZD Gauge deviation ZDC ZDIC ZDRC N/A ZDADH ZDSH ZDSM ZDSL ZDT ZDIT ZDRT N/A ZDV ZDX ZDY ZDZ ZDX Gauge X-axis deviation ZDXC ZDXIC ZDXRC N/A ZDXADH ZDXSH ZDXSM ZDXSL ZDXT ZDXIT ZDXRT N/A ZDXV ZDXX ZDXY ZDXZ ZDY Gauge Y-axis deviation ZDYC ZDYIC ZDYRC N/A ZDYADH ZDYSH ZDYSM ZDYSL ZDYT ZDYIT ZDYRT N/A ZDYV ZDYX ZDYY ZDYZ ZDZ Gauge Z-axis deviation ZDZC ZDZIC ZDZRC N/A ZDZADH ZDZSH ZDZSL ZDZT ZDZIT ZDZRT N/A ZDZV ZDZX ZDZY ZDZZ ZDZSM See statement of permission on page N/A = not allowed Note (3): The combinations in the [IC] and [RC] columns indicate the order to be followed in forming the Functional Identification of a controller device or function that also provides indication or recording Note (4): The combinations in the [C] column not have operator visible indication of measured variable, set point, or output signal, when used with discrete hardware single case instruments Note (5): The combinations in the [C] column may also be used for a controller function configured in a shared or distributed control system Note (6): The combinations in the [CV] column indicate the order to be followed in forming the Functional Identification for self-actuated control valves © 2003 by Béla Lipták General Considerations C 1.1 Flowsheet Symbols and P&I Diagrams GRAPHIC SYMBOL SYSTEM GUIDELINES See statement of permission on page 19 Tables 1.1o through 1.1r, Final Control Elements, consist of various geometric shapes that represent final control elements, such as control valves and their actuators, that are located in the process piping: General The future revised ISA Standard S5.1 (now ANSI/ISA5.01.01) establishes a graphic symbol system and functional identification for depicting instrument loop devices and functions, application software functions, and the interconnections between them that is logical, unique, and consistent in application with a minimum of exceptions, special uses, and requirements The graphic symbol system shall be used to depict instrumentation in text and in sketches and drawings When used with identification letters and numbers as described in the subsection titled “Identification System Guidelines,” it shall identify the functionality of each device and function shown The graphic symbol system provides methods for schematic loop diagramming, functional diagramming (see Section 1.2), and electrical schematic diagramming of any process or system that requires measurement, indication, control, modulation, or switching of variables Table 1.1g, Instrument Line Symbols, contains lines used to represent process connections and the measurement and control signals that connect instruments and functions to the process and to each other Tables 1.1h through 1.1k depict circles, squares, diamonds, hexagons, and lines used to represent the majority of hardware and software instruments and functions as follows: Table 1.1h, Discrete (Individual) Devices and/or Functions, represents discrete hardware instruments and/or functions that are implemented in nonmicroprocessor-based systems similar or equal to single-case transmitters, controllers, indicators, or recorders Table 1.1i, Shared Continuous Devices and/or Functions, represents shared and/or distributed software analog instruments and/or functions that are implemented in microprocessor-based systems similar or equal to distributed control or programmable logic control systems Table 1.1j, Shared On–Off Devices and/or Functions, represents shared and/or distributed on–off software instruments and/or functions that are implemented in microprocessor-based control systems similar or equal to a distributed control or programmable logic control systems Table 1.1k, Computer Devices and/or Functions, represents shared and/or distributed on–off software instruments and/or functions that are implemented in a computer-based control system Figures 1.1l and 1.1m illustrate some practical but not standardized P&ID symbology for a fieldbus system (DeviceNet) Table 1.1n, Primary Elements—Flow, describes various geometric shapes that represent primary measurement elements, such as orifice plates and thermocouples, that are located in the process piping © 2003 by Béla Lipták Table 1.1o–Control Valve Bodies Table 1.1p–Control Valve Actuators Table 1.1q–Self-Actuated Devices (includes such selfactuated elements as pressure control valves and pressure relief valves) Table 1.1r–Failure Position Indicators for Control Valves (indicates the position which the valve takes when/if the actuating power fails) Table 1.1s, Electrical Schematic Symbols, represents electrical circuit elements Specific industrial application examples of the graphic symbol system will be found in a future series of S5.1 (now ANSI/ISA-5.01.01) Technical Reports Sketches that are not all inclusive of acceptable methods of depicting instrumentation are included in the following text to illustrate the intent of the standard However, the individual symbols and their meanings are to be mandatory in the future, imminent standard Guideline Modifications These guidelines may be modified to suit the requirements of existing user-designed graphic symbols that are not included in this standard When modified symbols are adopted, they shall be fully described and detailed in the user/owner’s engineering or design standards Instrument Line Symbols In Table 1.1g, symbols represent the following: a) Instrument and device connections at process measurement points b) Connections to instrument power supplies c) Signals between measurement and control instruments and functions Lines shall be a) Fine in relation to process equipment and piping lines b) As short as possible and consistent with clarity Measurement and Control Devices and/or Function Symbols See Table 1.1h, Discrete (Individual) Devices and/or Functions, in which symbols represent discrete devices that perform continuous and/or on–off functions that not share control or display functions for the following: 20 General Considerations TABLE 1.1g Instrument Line Symbols (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Symbol 01 Application Instrument impulse line from process Instrument impulse line from equipment Analyzer sample line from process Functional instrument diagram signal lines 02 56 Heat (cool) traced instrument impulse line from process Heat (cool) traced instrument impulse line from equipment Heat (cool) traced analyzer sample line from process Type of tracing may be indicated as ET = electrical, RT = refrigerated, ST = steam, etc 03 Generic instrument impulse line connected to process line Generic instrument impulse line connected to equipment 04 Heat (cool) traced generic instrument impulse line connected to process line Heat (cool) traced generic instrument impulse line connected to equipment Process line or equipment may or may not be traced 05 Heat (cool) traced instrument connected to process impulse line Instrument impulse line may or may not be traced 06 Flanged instrument connection to process line Flanged instrument connection to equipment 07 Threaded instrument connection to process line Threaded instrument connection to equipment 08 Socket welded instrument connection to process line Socket welded instrument connection to equipment 09 Welded instrument connection to process line Welded instrument connection to equipment Practical industry tip: Use symbol for both seal weld on threaded connection as well as butt weld on larger sizes 10 AS 11 ES Instrument air supply Indicate supply pressure as required: AS-60 psig, AS-400 kPa, etc IA (instrument air) or PA (plant air) may be used for AS Use as required Instrument electric power supply Indicate voltage and type as required, e.g., ES-24 VDC, ES-120 VAC, etc Use as required Practical industry tip: Add note if it is coming from UPS 12 Undefined signal Use for PFDs Use for discussions or diagrams where type of signal, pneumatic or electronic, is not of concern 13 Pneumatic signal 14 Electric signal Electronic signal Functional instrument diagram signal lines 15 Hydraulic signal 16 Filled thermal element capillary tube 17 Guided electromagnetic signal Fiber optic cable Guided sonic signal 18 Unguided electromagnetic signal Unguided sonic signal Alternate radio communication link (see symbol 22) © 2003 by Béla Lipták 1.1 Flowsheet Symbols and P&I Diagrams 21 TABLE 1.1g Continued Instrument Line Symbols (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Symbol Application 19 Communication link or system bus, between devices and functions of a microprocessor-based system Industry tip: Use this for traditional DCS main data highway systems System internal software link 20 Shared communication link or bus (not system bus) between two or more independent microprocessor-based systems Shared data link from/between field located microprocessor-based devices and/or functions Industry tip: Use for fieldbus field devices 21 Dedicated communications link or bus (not system bus) between two or more independent microprocessor-based systems Dedicated data link from a field located microprocessor-based device and/or function 22 Dedicated radio communications link (not system bus) between radio transmitting and receiving devices and/or systems Unguided radio signal Alternate unguided electromagnetic signal (see symbol 18) 23 Mechanical link or connection 24 Signal connector Drawing-to-drawing signal connector Internal signal connector used to avoid long signal lines 25 Signal connector Internal signal connector used to avoid long signal lines Drawing-to-drawing signal connector See statement of permission on page TABLE 1.1h Discrete (Individual) Devices and/or Functions (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Symbol Location and Accessibility 01 Field or locally mounted Not panel or cabinet mounted Normally accessible to an operator 02 Central or main control room Front of main panel mounted Normally accessible to an operator 03 Central or main control room Rear of main panel mounted Not normally accessible to an operator 04 Secondary or local control room Field or local control panel Front of secondary or local panel mounted Normally accessible to an operator 05 Secondary or local control room Field or local control panel Rear of secondary or local panel or cabinet mounted Not normally accessible to an operator 06 Signal processor identifier located in upper right or left quadrant of symbols above Signal processor identifier attached to symbols where affected signals are connected See statement of permission on page © 2003 by Béla Lipták a) Measurement (transmitters, primary elements) b) Indication (indicators, annunciators) c) Control (controllers, control valves, switches, solenoids) Limited operator accessibility (setpoint changes, control mode transfers, etc.) and unlimited engineer or technician accessibility through location and enclosure methods are shown Table 1.1i covers analog, digital, and/or discrete shared control devices and/or functions for continuous control, indication, calculation, and so forth that are microprocessor based and configurable They communicate with each other and share control or display functions in applications such as distributed control and programmable logic systems Limited operator accessibility (setpoint changes, control mode transfers, and so forth) and unlimited engineer accessibility is through local or wide area communications networks, keyboards, and video displays as shown Table 1.1j deals with analog, digital, and discrete control devices and functions for on–off or binary control, indication, calculation, and so forth that are microprocessor based and configurable They communicate with each other and share control or display in distributed control and programmable logic systems Limited operator accessibility (setpoint changes, control mode transfers, and so on) and unlimited engineer accessibility is through local or wide area communications networks, keyboards, and video displays as shown The devices and functions in Table 1.1k include process plant computer-implemented regulatory and/or advanced control analog/digital/discrete (individual) control and indication functions that are mainframe computer or minicomputer based 22 General Considerations TABLE 1.1i Shared Continuous Devices and/or Functions (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) TABLE 1.1j Shared on–off devices and/or Functions (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No No Symbol Location and Accessibility 01 Dedicated single function device Field or locally mounted Not panel or cabinet mounted Normally accessible to an operator at device 02 Central or main console Visible on video display Normally accessible to an operator at console 03 Central or main console Not visible on video display Not normally accessible to an operator at console 04 Secondary or local console Field or local control panel Visible on video display Normally accessible to an operator at console 05 Secondary or local console Field or local control panel Not visible on video display Not normally accessible to an operator at console 06 Symbol Location and Accessibility 01 Field or locally mounted Not panel or cabinet mounted Normally accessible to an operator at device 02 Central or main console Visible on video display Normally accessible to an operator at console 03 Central or main console Not visible on video display Not normally accessible to an operator at console 04 Secondary or local console Field or local control panel Visible on video display Accessible to an operator at console 05 Secondary or local console Field or local control panel Not visible on video display Not normally accessible to an operator at console 06 Mathematical function located in upper right or left quadrant of symbols above Mathematical function attached to symbols where affected signals are connected Mathematical function located in upper right or left quadrant of symbols above Mathematical function attached to symbols where affected signals are connected See statement of permission on page See statement of permission on page Limited operator accessibility (setpoint changes, control mode transfers, etc.), and unlimited engineer accessibility is through local or wide area communications networks, keyboards, and video displays as shown Fieldbus P&ID Examples: DeviceNet Figures 1.1l and 1.1m show the practical methods used by one EPCM company in establishing a P&ID detail and markup for a low-voltage motor control plus a VFD motor control implemented with DeviceNet as the fieldbus It should be pointed out that these figures not completely conform to the ISA S5.1 (now ANSI/ISA-5.01.01) proposed standard and are a compromise born of necessity In Table 1.1n, symbols are pictorial representations of primary flow elements that generate a measurement or signal equal to, or a signal proportional to, a fluid flow rate or total flow In Table 1.1o, valve body symbols, when combined with valve actuator symbols, shall be used to represent control valves and solenoid valves as follows: Symbols 01 through 05 may be used as generic symbols to represent control and solenoid valve bodies The remaining symbols may be used when it is desired to more clearly indicate a specific valve body type © 2003 by Béla Lipták TABLE 1.1k Computer Devices and/or Functions (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Symbol Location and Accessibility 01 Undefined location Undefined visibility Undefined accessibility 02 Central or main computer Visible on video display Normally accessible to an operator at console or computer terminal 03 Central or main computer Not visible on video display Not normally accessible to an operator at console or computer terminal 04 Secondary or local computer Visible on video display Normally accessible to an operator at console or computer terminal 05 Secondary or local computer Not visible on video display Not normally accessible to an operator at console or computer terminal See statement of permission on page 1.1 Flowsheet Symbols and P&I Diagrams XL 81001 XA 81001 XCR 81001 L/R Status Common Start/Stop Trouble Command Alarm XSR 81001 XGM I xxx 81001 Available XL XA XCR XSR SI SC XGM Not Available 81001 81001 81001 81001 81001 81001 81001 DCS Control Run Status Common Start/Stop Trouble Command Alarm I xxx Run Status START P.B DCS ENABLE MCC HS 80001 MCC 23 H/O/A M DETAIL # VFD-01 M SC 81001 I xxx XGM 81001 XGM I xxx DETAIL # MLV-01 81001 XCR XSR XA XL XCR XSR XL XA MCC VFD M P&ID MARK UP MCC HS 80001 H/O/A M P&ID MARK UP FIG 1.1l Low voltage motor control on DeviceNet (detail and P&ID mark up) In Table 1.1s, contacts shall be shown in shelf condition Rising switch actuator will cause contacts to switch FIG 1.1m VFD motor control on DeviceNet (detail and P&ID mark up) Multivariable devices are indicators, recorders, and controllers that receive input signals from two or more primary elements or transmitters and control one manipulated variable Multifunction devices are controllers or switches that receive input signals from two or more primary elements or transmitters and control two or more manipulated variables Single variable or multivariable multipoint indicators and recorders for two or three points shall be drawn with bubbles either a) Tangent to each other in the same order, left to right, as the pen or pointer assignments: FR Multipoint, Multifunction, and Multivariable Devices and Loops Multipoint devices are indicators or recorders that may be single or multivariable and receive input signals from two or more primary elements or transmitters © 2003 by Béla Lipták ∗01 FT ∗01 PR 01 ∗ PT ∗01 TR ∗01 TT ∗01 24 General Considerations TABLE 1.1n Primary Elements—Flow (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Symbol 01 Description Generic flow element FE 02 Standard orifice plate Restriction orifice 03 Orifice plate in quick change fitting 04 Generic venturi tube, flow nozzle, or flow tube Notation required if used for more than one type 05 Venturi tube 06 Flow nozzle 07 Flow tube 08 Standard pitot tube 09 Averaging pitot tube 10 Turbine flowmeter Propeller flowmeter 11 Vortex shedding flowmeter 12 Target flowmeter 13 Magnetic flowmeter M TABLE 1.1o Final Control Elements—Control Valve Bodies (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Symbol Description 01 Generic two-way valve Straight globe control valve Two-way solenoid valve Gate valve 02 Generic two-way angle valve Angle globe control valve Angle solenoid valve 03 Generic three-way valve Three-way globe control valve Three-way solenoid valve Arrow indicates air failure or de-energized flow path 04 Generic four-way valve Four-way plug or ball control valve Four-way four ported on–off valve Arrows indicate air failure or de-energized flow paths 05 Four-way five ported on–off valve Arrows indicate air failure or de-energized flow paths 06 Butterfly valve 14 Positive displacement flowmeter 07 Two-way globe valve 15 Cone meter Annular orifice meter 08 Ball valve 16 Wedge meter 09 Plug valve 17 Coriolis flowmeter 10 Eccentric rotary disc valve 18 Sonic flowmeter Ultrasonic flowmeter 11 Diaphragm valve 19 Variable area flowmeter 12 Pinch valve 13 20 Open channel weir plate Generic damper Generic louver 21 Open channel flume 14 Parallel blade damper Parallel blade louver 22 Flow straightening vanes Flow conditioning element 15 Opposed blade damper Opposed blade louver See statement of permission on page © 2003 by Béla Lipták See statement of permission on page 1.1 Flowsheet Symbols and P&I Diagrams 25 TABLE 1.1p Final Control Elements—Control Valve Actuators (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) TABLE 1.1q Final Control Elements—Self-Actuated Devices (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No No Symbol 01 Description Generic actuator Spring-opposed diaphragm linear actuator 01 02 Spring-diaphragm actuator with positioner 02 03 Pressure-balanced diaphragm linear actuator Symbol XXX 03 Constant flow regulator Manual setpoint variable area flowmeter FI 04 05 06 Generic piston actuator May be linear or rotary 05 Piston actuator, single-acting, spring-opposed, with positioner 06 Flow sight glass Type shall be noted if more than one type used FG Generic flow restriction Single stage orifice plate as shown Note required for multistage or capillary tube types FO Restriction orifice hole drilled in valve plug Tag number may be omitted if valve is otherwise identified FO Piston actuator, double-acting, with positioner 07 Level regulator Ball float and mechanical linkage TANK 07 M Rotary motor-operated actuator May be electric, pneumatic, or hydraulic 08 S Automatic reset solenoid actuator Nonlatching solenoid actuator Dual solenoids may be used 09 S Manual or remote reset solenoid actuator Latching solenoid actuator R 10 S R R Manual actuator Hand actuator 12 Spring-, weight-, or pilot-actuated relief or safety actuator 13 Actuator with side-mounted handwheel 14 15 08 Backpressure regulator Internal pressure tap 09 Backpressure regulator External pressure tap 10 Pressure-reducing regulator Internal pressure tap 11 Pressure-reducing regulator External pressure tap 12 Differential-pressure regulator External pressure taps 13 Differential-pressure regulator Internal pressure taps Manual and remote-reset solenoid actuator Latching solenoid actuator 11 Automatic flow regulator XXX = FCV w/o indicator XXX = FICV w/integral indicator Variable area flowmeter with a manual regulating valve FI 04 Description 14 PG Pressure-reducing regulator w/integral outlet pressure relief and pressure gauge Actuator with top-mounted handwheel E H Electrohydraulic actuator May be linear or rotary action See statement of permission on page © 2003 by Béla Lipták 15 Generic pressure safety valve Pressure relief valve 16 Generic vacuum safety valve Vacuum relief valve 17 Generic pressure and vacuum relief valve Tank pressure and vacuum relief valve 26 General Considerations TABLE 1.1q Continued Final Control Elements—Self-Actuated Devices (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Symbol 18 b) Separate from each other, with pen or pointer number indicated preferably in upper right or left quadrant and a note defining instrument or device indicated in preferably lower right or left quadrant: Description 19 Temperature regulator Filled thermal system 21 TANK TSE 22 NOTE 23 TANK TR ∗ 01 NOTE FT NOTE TT 01 PT 01 ∗01 ∗ ∗ Note Indicated pen in 3-pen Recoder Thermal safety element Fusible plug or disk Generic moisture trap Steam trap Note required for other trap types T PEN #3 PR ∗ 01 FR ∗01 Pressure safety element Vacuum rupture disk Vacuum relief 20 PEN #1 PEN #2 Pressure safety element Pressure rupture disk Pressure relief Moisture trap with equalizing line Multipoint indicators and recorders for four or more points may be drawn with bubbles separate from each other, with point number indicated by adding a suffix to the tag numbers as follows: a) Single variable: T See statement of permission on page TE ∗01-01 TI TI TE ∗01-01 TI TE ∗01-02 ∗01-02 ∗01-03 ∗01-03 b) Multivariable: TABLE 1.1r Final Control Elements—Control Valve Air Failure Position Indication (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Method 01 Method Definition TE 01-01 ∗ UI UI PT ∗01-01 UI PT ∗01-02 ∗01-02 ∗01-03 ∗01-03 Fail to open position FO 02 Fail to closed position FC 03 Fail locked in last position Multivariable controllers may be drawn with bubbles for each measured variable input and for the output to the final control element; measured variable indicators may be: a) Shown: FL 04 Fail at last position Drift open PI PT 11 ∗ ∗ TI ∗ 11 LI ∗ 51 TT ∗51 FL/DO 05 Fail at last position Drift closed FL/DC UC 01 ∗ LT ∗ 21 FT 71 ∗ See statement of permission on page © 2003 by Béla Lipták UV 01 ∗ FO 21 FI ∗71 1.1 Flowsheet Symbols and P&I Diagrams 27 TABLE 1.1s Electrical Schematic Symbols (proposed for the next revision of ISA S5.1 [now ANSI/ISA-5.01.01] at the time of this writing) No Symbol Description 01 Normally open, single-circuit pushbutton switch contact Single-pole, normally open (SPNO) pushbutton switch contact Combine with symbols 06 or 07 to form toggle or rotary-actuated switches 02 Normally closed, single-circuit pushbutton switch contact Single-pole, normally closed (SPNC) pushbutton switch contact Combine with symbols 06 or 07 to form toggle or rotary-actuated switches 03 Normally open, double-circuit pushbutton switch contact Double-pole, normally open (DPNO) pushbutton switch contact Combine with symbols 06 or 07 to form toggle or rotary-actuated switches 04 Normally closed/normally open double-circuit pushbutton switch contact Double-pole, normally open/closed (DPNO/NC) pushbutton switch contact Combine with symbols 06 or 07 to form toggle or rotary-actuated switches 05 Two-position toggle or rotary-maintained position pushbutton switch actuator Combine with symbols 01 through 05 to form single-pole, double-throw (SPDT) or multipole double-throw (DPDT, TPDT, etc.) switches 06 Three-position toggle or rotary-maintained position pushbutton switch actuator Combine with symbols 01 through 05 to form single-pole, triple-throw (SPTT) or multipole, triple-throw (DPTT, TPTT, etc.) switches 07 Single-pole, single-throw (SPST) normally open toggle switch Form A switch contact 08 Single-pole, single-throw (SPST) normally closed toggle switch Form B switch contact 09 Single-pole, double-throw (SPDT) normally closed/normally open toggle switch Form C switch contact 10 Pressure switch actuator 11 Differential-pressure switch actuator 12 Liquid level switch actuator 13 Temperature switch actuator 14 Flow switch actuator 15 Foot switch actuator 16 Relay coil 17 Normally open relay contact 18 Normally closed relay contact 19 Connection convention A: Left = not connected Right = connected 20 Connection convention B: Left = not connected Right = connected © 2003 by Béla Lipták 28 General Considerations b) Assumed: PT 11 ∗ TT 51 ∗ UC 01 ∗ LT UV 01 ∗21 ∗ FT FO ∗71 Multifunction controllers shall be drawn with bubbles for each measured variable input and output to final control elements; measured variable indicators may be: a) Shown: PT ∗11 TI ∗51 TT ∗51 LI ∗21 UU ∗01 SP LT ∗21 SP PC ∗11 UV ∗01 FT ∗71 FO FC ∗71 PV ∗11 FV ∗71 FO FO b) Assumed: PT ∗11 TT ∗51 P&IDs: Practical Aspects and Practices in the EPC Industry UU ∗01 SP LT ∗21 SP PC ∗11 UV ∗01 FT ∗71 FO FC ∗71 FV ∗71 PV ∗11 FO FO Fieldbus Devices, Loops, and Networks Comments and Exceptions (Including Non-ISA Industrial Practice) Instrument and control systems staff working at engineering, procurement, and construction management (EPCM) companies had to improvise on P&ID symbols for fieldbus devices, loops, segments, and networks throughout the late 1990s and early 2000s This has been the case while waiting © 2003 by Béla Lipták for the draft standard work outlined in this section to be discussed and approved as the latest revision to ISA S5.1 (now ANSI/ISA-5.01.01) (For specific details on fieldbus technologies, please refer to later chapters and sections in this volume.) Certain techniques and shortcuts used by several EPCM companies, and how they have handled fieldbus symbology, will be mentioned in this subsection A few companies have generated their P&IDs using the proposed Instrument Line Symbol no 20 (Table 1.1g) as the shared data links or FOUNDATION™ fieldbus (FF) segments between field located microprocessor-based devices as well as FF host systems In this way, it is implicit that the devices connected by that symbol are fieldbus devices and not need any further symbology or identification on the P&IDs This symbol also has been used for other fieldbuses such as PROFIBUS PA, PROFIBUS DP, AS-i Bus, and DeviceNet (see Figures 1.1l and 1.1m) Another symbol used by the EPCM companies for fieldbus has been the Instrument Line Symbol no 19 (Table 1.1g), which is the current existing symbol (ANSI/ISA S5.11984[1992]) and normally the one used for data links and DCS data highways This has been done occasionally when the EPCM company’s client/owner had specific, custom P&ID symbology standards and was reluctant to change a worldwide standard to a new symbol such as no 20 Once again, any field devices such as transmitters and control valves that are connected together by Symbol no 19 are now known to be fieldbus-type devices The disadvantage is that the P&IDs must be studied carefully to determine real communication link, DCS data highway, system bus, or internal software link applications from the fieldbus applications Another EPCM company used the conventional analog electronic signal (Symbol no 14 in Table 1.1g) at the urging of its client but added the suffix “FB” to each fieldbus device bubble on the P&IDs Once again, this was not a standardized approach, and it led to ambiguity and misunderstanding It is highly recommended that the proposed draft revision Instrument Line Symbol no 20 (which we hope will be approved by the time this volume is released) be used for all types of fieldbus segments and networks Piping and instrument diagrams (P&IDs) are the basic documents describing a plant from mechanical and control point of view They are sometimes called mechanical flow diagrams (MFDs) by some EPC and operating companies Process flowsheets/diagrams (PFDs) are used and generated by process design engineering in the very early stage of the frontend engineering phase and not normally include ISA symbols except in the most elementary fashion However, they are the starting point for P&ID development The P&ID life cycle extends through the feasibility study, project estimate, detailed engineering phase, construction phase, precommissioning, commissioning, and, finally, to exploitation of the plant According to which phase the 1.1 Flowsheet Symbols and P&I Diagrams project is in, the P&IDs show different level of details to suit various needs 1) During the feasibility study, not all equipment and lines are shown; only the major ones appear, such as used to follow the path of authorizations, obtain of financing, and so on At this stage, only major equipment is sized, such as to show environmental impact, and effluent systems are studied to comply with the information requested by various environmental authorities Only major lines are shown, without sizing information Very few instruments and control loops are shown, and then only in the most simplified manner 2) During the project estimate, all equipment is shown, but without auxiliary services such as cooling water to machinery The lines are sized, and their material and rating are shown All control loops are shown, or at least all transmitters, local instruments, and control valves All motor-operated valves and safety valves are shown and are sized if possible Small-bore/diameter piping (